Motor operated multiple blade shears



Jan. 13, 1948. c. L. BEARD MOTOR OPERATED MULTIPLE BLADE SHEARS Filed June 6, 1944 DUAI.

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Cittomeg Patented Jan. 13, 1948 UNITED STATES PATENT QFFICE MOTOR OPERATED MULTIPLE BLADE SHEARS Charles L. Beard, Lancaster, Pa.

Application June 6, 1944, Serial No. 538,916

2 Claims.

This invention relates to a metal cutting tool, and an object of the invention is to provide a simple, practical and efiicient tool by the use of which sheet metal may be readily out along either curved or straight lines in manufacturing and repairing automobile and airplane bodies and for many other uses where sheet metal is employed.

A further object of the invention is to provide a power actuated multiple blade cutter, the blades of which are caused to come into play, at different intervals.

Other objects and advantages will be understood as the specification is considered in connection with the accompanying drawings, in which:

Figure 1 is a longitudinal sectional View through my improved cutter;

Figure 2 shows the cutter blades and operating cam in the positions assumed at the start of the cutting operations and as shown in Figure 6;

Figures 3, 4, 5 and 6 show the several respective positions assumed by the cam and cutter blades as the cam is rotated in four progressive stages of approximately 45, 90, 120 and 180 each;

Figure 7 is a section taken along the line 1-7 of Figure 1; and

Figure 8 is a fragmentary section taken on the line 8-8 of Figure 1.

Referring more particularly to the drawings, l designates a body member, preferably in the nature of a casting, having a chamber 2 extending therethrough from end to end thereof for accommodating a pair of spaced outer cutting blades 3--3, an intermediate cutter blade 3", and a shaft 4 and cam 5 for actuating the blades.

The elongated cutter blades, are mounted intermediate their ends upon a pintle 5, suitably anchored at its ends in the casing side walls or bifurcations I. Each of the two outer spaced blades 3-3 has a downwardly facing cutting edge 9 while the intermediate blade 3" is formed with an upwardly facing cutting edge It. A pair of oppositely disposed screws 3, mounted in the walls I, extend into the chamber 2 and bear against the two outer cutter blades 33'. These screws provide means for adjusting the clearance between the three blades, according to the various thickness and types of materials on which the tool is to be used.

The inner ends of the two outer blades 3-3 are resiliently maintained in constant engagement with the cam 5, by means of a coil spring II, and a leaf spring l2 functions in a similar manner with respect to the lower or intermediate blade 3". The cam 5 is integrally formed on or 2 suitably secured to the shaft 4, and the latter is rotatably mounted in a bearing l3, suitably secured to the walls of chamber 2. Consequently when the reduced outer end l4 of the shaft is inserted in and driven from the chuck of an electric drill, not shown, the inner ends of the blades 3-3 and 3 will be rapidly oscillated due to the combined action of the cam 5 and springs H and I2. Y

It will also be seen that the cutting edges of each of the respective blades 3 and 3 come into scissors like cutting action with blade 3" twice during one complete rotation of the cam, the length of interval depending upon the shape of the cam. Thus, assuming that the electric drill is rotating the shaft 0 and cam 5 in a clockwise direction the blade action is as follows:

Starting from Figure 2 position, the cam 5 will be rotated in a clockwise direction. Four respective stages of approximately 45, and each are illustrated in Figures 3, 4, 5 and 6. It will be noted that in the rotation of the cam through 180 the blades have been operated through a complete cutting cycle and continued rotation of the cam through 360 would repeat this cutting cycle.

On studying Figures 2, 3, 4, 5 and 6, it will be apparent that, as the cam is rotated, the blades 3 and 3 move relative to each other and also move relative to blade 3". The frequencies of oscillation of all three blades 3. 3 and 3" are the same and depend on and vary with the speed of rotation of cam 5. Each of the blades 3, 3 and 3 completes in one cutting cycle or one half revolution of cam 5, a complete opening and closing movement. However, the movements of the respective blades are not in phase with each other. It will be apparent that the difierence in phase of oscillation of the blades 3 and 3 will depend upon the spacing between their inner cam contacting ends} If the inner ends of blades 3 and 3' are not spaced from each other so that they ride upon approximately the same point of the edge of cam 5, the inner ends of blades 3 and 3 would rise and fall together and be in phase. However, as the inner ends of blades 3 and 3' are spaced from each other, a difference in phase is introduced into their respective movements. As the spacing between blades 3 and 3' is increased, the phase difierence between these blades is correspondingly increased. Since a phase difference in the oscillation of blades 3 and 3' will cause one of these blades to engage blade 3" in a closing scissors movement, while the other blade engages blade 3 in an opening scissors movement, a sufiicient spacing of the inner ends of blades 3 and 3 would result in a continuous cutting operation, that is the blades 3 and 3' would oscillate 180 out of phase with respect to each other.

One cycle of cutting, with the blades 3, 3' and 3" and cam 5 as illustrated in the drawings, will be hereinafter set forth so as to more clearly describe the substantially continuous cutting operation thereof. By way of illustration, one complete cycle will be considered. The 180 revolution of cam 5 will be divided into eight parts each covering 225.

The following table illustrates substantially the relative movements of the inner ends of blades 3, 3' and 3" as cam 5 rotates through 180. It is apparent that, as the inner ends of blades 3 and 3' move upwardly with respect to the inner end of blade 3", there is a cutting operation performed by the forwardor cutting edges of the blades. In describing this operation, the rotation of the cam 5 is considered as starting from the position illustrated in Figure 2 and rotating clockwise to the position illustrated in Figure 6.

4 or both of the latter, as distinguished from the spasmodic action of prior cutters. The width of the strip cut from the work sheet, not shown, is substantially that of the distance separating the two blades 3 and 3'.

Having thus described my invention, what I claim is:

1. A cutting tool comprising a body having a chamber therein, a pair of outer parallelly disposed cutting blades and an intermediate blade arranged therebetween at an angle thereto and cooperating therewith, all of said blades being movable and having tail portions and cutting portions, the cutting portion of said intermediate blade being opposed to the cutting portion of said outer blades, a pintle for pivotally connecting said blades together in said chamber and to the walls of said body, a power driven shaft extending into said body and cam means carried by said shaft rotatably engageable with the tail portions of said blades to effect movement of said blades at different intervals.

2. A cutting tool comprising a body having a chamber therein, a pair of outer parallelly dis- Cutting Operation of 3' and 3 Cutting Operation of 3 and 3 Motion of Blade 3" Motion of Blade 3 Rotation of Cam Motion of Blade 1' down slow. up slow..." up faster.

d slow cut On studying the above table, it will be noted that there is a cutting operation when the inner ends of cutter blades 3 and 3" are both moving upwardly and also when the inner ends of cutter blades 3 and 3" are both moving upwardly. The reason for the cutting action in these cases is that the upward movement of the inner ends of blades 3 and 3' is faster than the upward movement of the inner ends of blade 3".

It should be noted here that the action of the springs II and 12, as well as the force of the sheet of metal being fed between the cutting blades, causes the inner or cam ends of the blades to closely adhere to or follow the contour of the cam.

Movement of the blades from Figure 6 back to Figure 2 position, thus completing one full cycle, will be obvious from the foregoing and it will be clear that a substantially continuous cutting action is at all times taking place between blade 3" and either of blades 3 and 3 or both of the latter as distinguished from the spasmodic action of prior cutters. The width of the strip cut from the work sheet, not shown, is substantially that of the distance separating the two blades 3 and 3'.

Movement of the blades from Figure 5 back to Figure 2 position, thus completing one full cycle, as illustrated in Figure 6, will be obvious from the foregoing and it will be clear that a continuous cutting action is at all times taking place between blade 3" and either of blades 3 and 3' posed cutting blades and an intermediate blade arranged therebetween at an angle thereto and.

cooperating therewith, a common pivot for securing all of said blades to the walls of said chamber, said blades having tail portions and cutting portions, the cutting portion of said intermediate blade being opposed to the cutting portion of said outer blades, a pintle for pivotally connecting said blades together in said chamber and to the walls of said body, a power driven shaft extending into said body and cam means carried by said shaft rotatably engageable with the tail portions of said blades to efiect movement of said blades at different intervals to cause substantially constant cutting movement between at least two of said blades and means for adjusting the clearance between the three blades.

CHARLES L. BEARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,559,082 Friederici Oct. 27, 1925- 1,710,950 Robertson Apr. 30, 1929 1,733,374 Kalgren Oct. 29, 1929 1,484,598 Weniger Feb. 19, 1924 2,273,376 Reynolds Feb. 17, 1942 

